(1) Field of the Invention
The present invention generally relates to a projector, and particularly to a heat dissipating device of a projector.
(2) Description of the Prior Art
Please referring to FIG. 1. A conventional projector 2 includes a housing 14, an optical engine module 6 and a light source 8. A front end 202 is on one end of the housing 14 where a projection lens of the optical engine module 6 extends to. A back end 204 is opposite to the front end 202. The light source 8 is disposed on one end of the optical engine module 6 for providing the optical engine module 6 with light. When providing light, the light source 8 also generates plenty of heat. Therefore, a heat dissipating device 4 is needed for dissipating heat accumulated inside the projector 2.
A conventional heat dissipating device 4 includes an axial fan 10, a blower 12 and a air vent 16. The axial fan 10 is disposed near one side (a first side 804) of the light source 8. The first side 804 is adjacent to the back end 204 of the projector 2. The blower 12 is disposed near a front edge of the light source 8 on the first side 804, that is, near a light emitting opening of the light source 8. The axial fan 10 and the blower 8 are both disposed near the same side, the front side 804, of the light source 8. The air vent 16 is disposed on the front end 202 of the housing 14 of the projector 2. The air vent 16 is disposed corresponding to a hot airflow generated by the heat dissipating device 4.
An airflow generated by the axial fan 10 flows from the first side 804 toward another side of the light source 8 (a second side 802). The second side 802 is adjacent to the front end 202 of the projector 2. The hot airflow flows out of the projector 2 through the air vent 16. An airflow generated by the blower 12 flows from the first side 804 into the light source 8 and then carries the heat out from the light source 8. Thereon, the airflow generated by the blower 12 flows toward the second side 802 and flows out of the projector 2 with the heat through the air vent 16. However, the distance between the inside of the light source 8 and the air vent 16 is very short. In other words, the distance that the hot airflow flows from the inside of the light source 8 to the air vent 16 is very short. As a result, the hot airflow easily flows out through the air vent 16 directly, so the vent 16 is heated by the hot airflow directly. Local temperature of the air vent 16 is very high and beyond the safety regulation. Therefore, when a fence of the air vent 16 is manufactured, the fence has to be especially made of expensive heat resistant material. Thus, the cost of the projector 2 is increased.
FIG. 2 illustrates temperature distribution diagram of the conventional vent 16. As shown in FIG. 2, several points of the air vent 16 are selected to measure the temperature. The temperature of partial regions are higher than 90° C., and the difference among regions is enormous. High temperature concentrates in specific regions. The highest temperature is 91° C. and very close to 95° C. of the highest temperature of the safety regulation. Therefore, it is a very urgent issue to unify the temperature of the air vent 16.
Besides, the projector 2 further includes a color wheel 18 disposed on an optical path of the light source 8. When the blower 12 is disposed on the first side 804, the color wheel 18 is disposed on the second side 802 for avoiding interfere with the blower 12. The color wheel 18 is far away from the axial fan 10. As a result, the color wheel 18 is not cooled properly, and a hot area is formed around the color wheel 18. The color wheel 18 is damaged due to the high heat. Furthermore, the airflow generated by the blower 12 flows through an air outlet of the light source 8 on the second side 802. The air outlet of the light source 8 is very close to the air vent 16. Therefore, light leaks easily.